Political trends come and go in response to events. Gun control was the rage during the Clinton administration, but over the past decade or so it became an obsolete cause. After the horrific crimes in Newtown and Aurora, though, it's staging a comeback.

There have been shootings at shopping malls over the years in Baltimore and across the country. But incidents like the one Saturday in Columbia — inside the mall and near large crowds — are relatively rare.
Jan. 25, 2014: A gunman and two...